COMPARISON OF PROPELLEE AND REACTION- 

 PROPELLED AIRPLANE PERFORMANCES ^ 



By Benson Hamlin 



Project Engineer 



and 



F. Spenceley 



Performance Group AeroAynamicist 



Bell Aircraft Corporation 



INTRODUCTION 



Coincident with the development ,of successful turbojet power plants 

 for aii'craf t, a broad new field of propulsion has come to light. Power- 

 plant research and development has progressed so rapidly that a wide 

 choice of power plants is now available to the aircraft manufacturer, 

 who as yet has had little opportunity to demonstrate the practical 

 applications. The purpose of this paper is to evaluate the airplane- 

 performance potentialities of four types of widely differing power 

 plants and to indicate their trends and particular fields of application. 



Conventional power plants of the reciprocating, internal-combustion 

 type, both direct and indirect air-cooled, have been extended to com- 

 pounding with a gas-turbine wheel operated by the normal exhaust 

 gases and delivering the power thus generated back into the crank- 

 shaft. The independent gas turbine is also available for use in con- 

 junction with the propeller, in which case approximately 80 percent 

 of the energy in the gases is absorbed by the turbine to drive the 

 propeller and the remainder is utilized in the form of reaction propul- 

 sion. Air-stream engines include the turbojet, reso-jet (or intermit- 

 tent duct), and the ram- jet (or athodyd), all of which are reaction 

 motors depending upon atmospheric air supply. A third classifica- 

 tion of available power plants consists of dry- or liquid-fuel types of 

 rocket motors, which are distinguished principally by the fact that 

 atmospheric oxygen is not used for combustion as in the case of pther 

 power plants. 



^ Presented before a closed meeting of the Institute of the Aeronautical Sciences, Holly- 

 wood, Calif., Aug. 15, 1945. Reprinted by permission from the Journal of the Aeronautical 

 Sciences, vol. 13, No. 8, August 1946. 



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